.240 Weatherby Magnum

History

Introduced in 1968 for the Weatherby Mark V rifle, the .240 Weatherby was yet another addition to Roy Weatherby’s ‘worlds fastest’ family of cartridges. The .240 Weatherby still retains its status as the worlds fastest commercially available 6mm, mostly because it is very difficult to drive 6mm projectiles any faster due to case to bore expansion ratio limitations. In fact, it was because of these limitations that Weatherby chose the .30-06 cartridge case as the parent case design for the .240. No other Weatherby cartridge utilizes such a small case. The .240 is essentially the .30-06 necked down to 6mm (.243”) with a belt added (for a ‘magnum’ appearance) and a double radius improved shoulder.

The .240 is very similar (velocity potential) to the .240 Holland and Holland Nitro Express released in 1923 and also the 6mm-06 and 6mm-.284 wildcat cartridges. The .240 has never been a highly popular cartridge for reasons that will be discussed in the performance section ahead. Nevertheless, for 6mm fans, the .240 Weatherby is a real powerhouse.

Performance

The .240 Weatherby is a powerful, fast killing medium game cartridge but is not without contradictions. This cartridge produces far too much recoil and noise to be considered ideal for those who are either recoil shy or have sustained shoulder injuries. At the same time, the .240 lacks the ability to utilize heavy projectiles in comparison to wider bores such as the 7mm08 which is able to utilize 140 grain bullets, it produces a relatively flat trajectory and produces a similar level of recoil. The similar powered .25-06 is able to utilize 120 grain bullets,

The .240 puts both premium and conventional projectiles through considerable stress at close ranges. Although close range wounding can be immensely traumatic, bullet blow up is always a risk with all bullet brands apart from the Barnes TSX. For these reasons, the .240 is best viewed as being suitable for the same range of game as the .243 Winchester but with an added X factor.

The .240 excels on light game weighing between 40 and 60kg (90-130lb), is ideal for game weighing between 60 and 80kg (130-180lb) but like all 6mm’s requires careful shot placement as game weights become heavier and heavier. The .240 is a more violent, spectacular killer than other 6mm’s and produces fast killing out to ranges exceeding 300 yards compared to the more usual 200 yards. Nevertheless, these great features are soon lost if the .240 is expected to produce just as dramatic kills on game weighing 150+kg (330lb) with ordinary shot placement. Yes, the .240 can handle heavy game the size of Elk and Sambar but as previously suggested, there are several cartridges which are able to utilize heavier, wider, more effective killing bullets with similar trajectories and recoil.

Factory Ammunition

The .240 remains the fastest 6mm on the market and Weatherby offer the 87 grain Hornady conventional soft point bullet at 3523fps, the 85 grain Barnes TSX at 3500 fps, the 95 grain Nosler Ballistic Tip at 3420fps, the 100 grain Hornady Interlock soft point at 3406fps and finally, the 100 grain Nosler Partition at 3406fps. Although .240 factory loads are chronographed in test barrels, .240 factory ammunition in sporting rifles comes awfully close to stated velocities. These velocities are near the practical limit for which bullets can be driven through a 6mm diameter bore.

The Hornady 87 grain soft point has great trouble staying together at both close and moderate range impact velocities. Also, rather than blow into size-able fragments, this projectile tends to vaporize into molten dust. This load is best utilized for varminting and even with bullet blow up, kills on light medium game are not spectacular.

As can be expected, the 85 grain Barnes and 100 grain Partition are the best performers in the .240. Nevertheless, while these loads have plenty of power, best results are obtained on medium game weighing between 40 and 80kg and up to 100kg (220lb). The Partition is an explosive, violent performer capable of deep penetration providing it is used on light to medium boned deer. If used on heavy animals, there is a risk of bullet blow up and shallow penetration. The 85 grain Barnes TSX is not so sensitive. This is a spectacular killer on medium game and is the go-to bullet when using the .240 on either Boar or any game weighing above 80kg.

Hand Loading

With an identical rim diameter to the .30-06 it is a relatively simple proposition to re-barrel any standard action rifle to .240 Weatherby magnum. Brass for the .240 is readily available from Weatherby dealers. Case capacities are, as can be expected, near identical to the .25-06 and both cartridges produce best performance with similar burning rate powders. Suitable powders include those in the H4831, IMR4831 range. From the 26” barreled Weatherby, realistic safe working maximum velocities include 3500fps with 85 grain bullets, 3450fps with 95 grain bullets and 3400fps with 100 grain bullets.

When hand loading, conventional 6mm bullets really struggle to hold together at high impact velocities. This narrows projectile choice for medium game considerably. Of the conventional projectiles available, the 95 grain Hornady SST is the stoutest on the market. Nevertheless, both the brilliant 95 grain Hornady SST and the just as useful Nosler Ballistic Tip are made to work beyond reasonable expectations inside 150 yards. Still, both are suitable for game weighing between 40 and 60kg (90-130lb) at close ranges. Beyond 150 yards and out to 300 yards, these two projectiles produce outstanding results on deer weighing up to 80kg (180lb). Both are able to produce clean kills on heavier game but hunters must bear in mind that to do so is pushing these projectiles beyond their design limitations.

Better all rounder’s include the 85 grain Hornady InterBond and 90 grain Swift Scirocco bonded bullets. These two projectiles find their strengths in the .240 platform and really shine. Both are good medium game bullets from zero to 300 yards and work far better in the .240 than in the slower 6mm’s. These projectiles are really the ultimate for the .240 when used on medium game weighing between 60 and 100kg (130-220lb). The InterBond and Scirocco produce the same explosive wounding as the Partition and the reliability of the Barnes.

The 85 grain Barnes is a very good projectile for tough animals such as wild boar. Although the Barnes suffers a cut off point in wide wounding at impact velocities of around 2600fps, the .240 keeps the 85 grain TSX above 2600fps out to a massive 350 yards. The .240 really brings this projectile to life and increases its versatility immensely.

Closing Comments

The .240 Weatherby Magnum is certainly a unique cartridge. While it is quite capable of handling heavy deer species such as Elk and Sambar, often with little fuss, its true strengths are found when, like other 6mm’s, it is utilized as a lighter medium game cartridge. In this role, the .240 is a spectacular killer and does so out to a useful range. The .240 is also of course, an excellent varmint cartridge.

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ABOUT US

We are a small, family run business, based out of Taranaki, New Zealand, who specialize in cartridge research and testing, and rifle accurizing.